Expression of OB receptor splice variants during prenatal development of the mouse

In adult animals, signaling through the leptin receptor (OB-R) has been sho wn to play a critical role in fat metabolism. However, it is not known when these receptors are first expressed and what their role may be during embr yonic development. To date, at least 6 splice variants of the OB-R have bee n identified. Although the function of each of these individual splice vari ants are unknown, only one of them, ob-r(L), encodes a receptor with a long intracellular domain that is implicated in OB-R signaling. In this study w e have used in situ hybridization to examine the localization of OB-R splic e variants during embryonic development of C57B1/6J mice. Using a probe, ob -r, that recognizes all of the splice variants, ob-r mRNA was found to be d istributed in developing bone, mesenchyme, notochord and liver. In addition , epithelial structures including leptomeninges, choroid plexi and hair fol licles also expressed ob-r. No ob-r mRNA was detected in the CNS. ob-r(L), expression was only detected in notochord, bone and mesenchyme. The differe ntial expression of these two mRNA isoforms suggests that the extracellular and intracellular domains of the OB receptor perform different biological functions.